The present invention relates to semiconductor devices and, more particularly, to a method of forming an isolation layer of a semiconductor device employing a Shallow Trench Isolation (STI) process.
In the process of manufacturing semiconductor devices, an isolation layer is formed in order to electrically insulate semiconductor devices (such as transistors) formed over a substrate. Conventionally, the isolation layer was formed by a LOCOS process of a local oxidation method. As the level of integration of devices has increased, the isolation layer is currently formed by a STI process.
The STI process is performed such that an isolation region of a semiconductor substrate is etched to form trenches. The trenches are filled with an insulating material. The STI process for manufacturing semiconductor devices overcomes the occurrence of a bird's beak in the LOCOS process. However, as the level of integration of devices increases, the width of each trench decreases. This makes it difficult to fill the trenches with insulating material.